Flood forecast for Red River in Manitoba improves

The worst-case scenario for Red River flooding in Manitoba this spring is not as bad as it looked a month ago.

In its second flood outlook of the season, issued Wednesday, Manitoba's hydrologic forecast centre has lowered the potential peak of the Red River flood this spring.

Under an unfavourable weather scenario — that is, where heavy rain or snow falls along the Red River drainage basin in the coming weeks — provincial flood forecasters now expect flows along the Red in 2022 to be no higher than they were in 2011.

That marks an improvement from a month ago, when forecasters predicted flooding similar to that in 2009 under an unfavourable weather scenario.

The 2009 Red River flood was the worst since the flood of the century in 1997. The peak flow for the river just south of Winnipeg maxed out that spring at 97,000 cubic feet per second.

That's roughly equivalent to 1.5 swimming pools flowing past St. Adolphe, Man. every second.

The 2011 flood peaked at 78,000 cubic feet per second.

A flood akin to the 2011 flood would still be considered major. The Red would spill over its banks, require some communities to close their ring dikes and close the southernmost portion of Highway 75.

However, that level of flooding would not threaten communities within those dikes, which have been raised high enough to withstand the flooding on the scale of the Flood of the Century in 1997, which crested south of Winnipeg at 138,000 cubic feet per second.

"The residents of the Red River Valley and the residents in the in the City of Winnipeg are fine in terms of being able to receive the water that we get from south of the border," said University of Manitoba civil engineering professor Jay Doering, an expert in hydrology.

"I really do believe that we are well equipped to handle what we potentially see coming at us."

The 2022 flood may end up being far less severe than the 2011 flood.

Provincial flood forecasters say under average weather conditions in the coming weeks — a normal amount of rain or snow — the flood this spring will be similar to the one in 2020.

The forecasters say under favourable conditions — very little rain or snow — the 2022 flood will look a lot like the one in 2019.

Neither the 2019 nor 2020 floods were memorable events. But under all three scenarios for the Red River this spring, the Red River Floodway control structure would be put into action.

25th anniversary of Flood of the Century

This spring will also mark the 25th anniversary of the Flood of the Century, which swamped the town of Ste. Agathe, Man., forced 30,000 people in southern Manitoba out of their homes and came within a couple of bad weather days from overwhelming Winnipeg's flood defences.

"It's certainly  not something that we're going to be holding a parade for, like a celebration," said Curtis Claydon, the Ritchot municipal councillor responsible for Ste. Agathe. 

The town is now protected by a ring dike that surrounds new residential developments. 

"I think you can look at 25 years and see how the community has progressed and and flourished since then," said Claydon, who moved to Ste. Agathe after the flood.

The entire Manitoban portion of the Red River Valley is more resilient now than it was in 1997, Doering added.

"We've come a long way since then. We've made significant investments in the upgrade to the [floodway] control structure. The floodway channel itself has been expanded out to accommodate a flood of a scale we'd expect on average once every 700 years," he said.

"There were eight ring dikes in the community then. There are now 16 ring dikes in the community, and everyone has been forced to build their property to 1997 plus two feet."

Provincial flood forecasters are predicting moderate to major flooding along several tributaries of the Red River this spring: the Pembina and Roseau rivers.

Forecasters expect moderate flooding on the Souris River in southwestern Manitoba and minor to moderate flooding along the Assiniboine River.